Merge pull request #1 from jfacorro/missing-slice-implementation-for-Enumerable

Implement missing slice function for Enumerable protocol

Author: jfacorro

lib/array.ex

@@ -371,6 +371,15 @@ defimpl Enumerable, for: Array do
   def reduce(%Array{content: c}, acc, fun) do
     Enumerable.reduce(:array.to_list(c), acc, fun)
   end
+
+  def slice(arr) do
+    slice_fun = fn (start, length) ->
+      for i <- start..(start + length - 1) do
+        Array.get(arr, i)
+      end
+    end
+    {:ok, Array.size(arr), slice_fun}
+  end
 end
 
 defimpl Collectable, for: Array do

mix.exs

@@ -6,26 +6,14 @@ defmodule Array.Mixfile do
      version: "1.0.1",
      elixir: ">= 1.0.0",
      description: "An elixir wrapper library for Erlang's array.",
-     package: package,
-     deps: deps]
+     package: package(),
+     deps: deps()]
   end
 
-  # Configuration for the OTP application
-  #
-  # Type `mix help compile.app` for more information
   def application do
     [applications: [:logger]]
   end
 
-  # Dependencies can be Hex packages:
-  #
-  #   {:mydep, "~> 0.3.0"}
-  #
-  # Or git/path repositories:
-  #
-  #   {:mydep, git: "https://github.com/elixir-lang/mydep.git", tag: "0.1.0"}
-  #
-  # Type `mix help deps` for more examples and options
   defp deps do
     [{:earmark, ">= 0.0.0", only: :dev},
      {:ex_doc, "~> 0.6", only: :dev}]

test/array_test.exs

@@ -87,7 +87,7 @@ defmodule ArrayTest do
   test "fix" do
     a = Array.new()
     a = Array.set(a, 100, 0)
-    
+
     a = Array.fix(a)
     assert_raise ArgumentError, fn ->
       Array.set(a, 101, 0)
@@ -405,7 +405,7 @@ defmodule ArrayTest do
   test "to_erlang_array" do
     a = Array.from_list([1,2,3])
     ea = Array.to_erlang_array(a)
-    
+
     assert :array.is_array(ea)
     assert 3 == :array.size(ea)
     assert 1 == :array.get(0, ea)
@@ -454,6 +454,14 @@ defmodule ArrayTest do
     assert 6 == sum
   end
 
+  test "Enumerable.slice" do
+    slice = Enum.slice(Array.from_list([1,2,3,4,5]), 1, 2)
+    assert [2,3] == slice
+
+    slice = Enum.slice(Array.from_list([1,2,3,4,5]), 3, 1)
+    assert [4] == slice
+  end
+
   test "Collectable.into" do
     a = Enum.into([1,2,3], Array.new())
     assert Array.is_array(a)